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Exercise and Sport Sciences Reviews Jan 2018Endothelium-dependent vasodilation is reduced after acute exercise or after high intraluminal pressure in isolated arterioles from sedentary adults but not in arterioles... (Review)
Review
Endothelium-dependent vasodilation is reduced after acute exercise or after high intraluminal pressure in isolated arterioles from sedentary adults but not in arterioles from regular exercisers. The preserved vasodilation in arterioles from exercisers is hydrogen peroxide (H2O2) dependent, whereas resting dilation is nitric oxide (NO) dependent. We hypothesize chronic exercise elicits adaptations allowing for maintained vasodilation when NO bioavailability is reduced.
Topics: Adaptation, Physiological; Cardiovascular Diseases; Endothelium, Vascular; Exercise; Humans; Hydrogen Peroxide; Microcirculation; Nitric Oxide; Sedentary Behavior; Vasodilation
PubMed: 28816705
DOI: 10.1249/JES.0000000000000130 -
International Journal of Molecular... Jun 2018Chronic venous disease (CVD) is a common pathology, with significant physical and psychological impacts for patients and high economic costs for national healthcare... (Review)
Review
Chronic venous disease (CVD) is a common pathology, with significant physical and psychological impacts for patients and high economic costs for national healthcare systems. Throughout the last decades, several risk factors for this condition have been identified, but only recently, have the roles of inflammation and endothelial dysfunction been properly assessed. Although still incompletely understood, current knowledge of the pathophysiological mechanisms of CVD reveals several potential targets and strategies for therapeutic intervention, some of which are addressable by currently available venoactive drugs. The roles of these drugs in the clinical improvement of venous tone and contractility, reduction of edema and inflammation, as well as in improved microcirculation and venous ulcer healing have been studied extensively, with favorable results reported in the literature. Here, we aim to review these pathophysiological mechanisms and their implications regarding currently available venoactive drug therapies.
Topics: Chronic Disease; Humans; Microcirculation; Varicose Ulcer; Vascular Diseases; Veins
PubMed: 29874834
DOI: 10.3390/ijms19061669 -
Anesthesiology Dec 2019
Topics: Abdomen; Microcirculation; Mouth Floor; Myocardial Contraction
PubMed: 31567361
DOI: 10.1097/ALN.0000000000002995 -
Toxins Jul 2018Individuals at all stages of chronic kidney disease (CKD) have a higher risk of developing cognitive disorders and dementia. Stroke is also highly prevalent in this... (Review)
Review
Individuals at all stages of chronic kidney disease (CKD) have a higher risk of developing cognitive disorders and dementia. Stroke is also highly prevalent in this population and is associated with a higher risk of neurological deterioration, in-hospital mortality, and poor functional outcomes. Evidence from in vitro studies and in vivo animal experiments suggests that accumulation of uremic toxins may contribute to the pathogenesis of stroke and amplify vascular damage, leading to cognitive disorders and dementia. This review summarizes current evidence on the mechanisms by which uremic toxins may favour the occurrence of cerebrovascular diseases and neurological complications in CKD.
Topics: Animals; Blood Vessels; Brain; Cerebrovascular Disorders; Cognition Disorders; Humans; Microcirculation; Toxins, Biological; Uremia
PubMed: 30037144
DOI: 10.3390/toxins10070303 -
Physiological Reports May 2022In the vascular system, an extensive network structure provides convective and diffusive transport of oxygen to tissue. In the microcirculation, parameters describing... (Review)
Review
In the vascular system, an extensive network structure provides convective and diffusive transport of oxygen to tissue. In the microcirculation, parameters describing network structure, blood flow, and oxygen transport are highly heterogeneous. This heterogeneity can strongly affect oxygen supply and organ function, including reduced oxygen uptake in the lung and decreased oxygen delivery to tissue. The causes of heterogeneity can be classified as extrinsic or intrinsic. Extrinsic heterogeneity refers to variations in oxygen demand in the systemic circulation or oxygen supply in the lungs. Intrinsic heterogeneity refers to structural heterogeneity due to stochastic growth of blood vessels and variability in flow pathways due to geometric constraints, and resulting variations in blood flow and hematocrit. Mechanisms have evolved to compensate for heterogeneity and thereby improve oxygen uptake in the lung and delivery to tissue. These mechanisms, which involve long-term structural adaptation and short-term flow regulation, depend on upstream responses conducted along vessel walls, and work to redistribute flow and maintain blood and tissue oxygenation. Mathematically, the variance of a functional quantity such as oxygen delivery that depends on two or more heterogeneous variables can be reduced if one of the underlying variables is controlled by an appropriate compensatory mechanism. Ineffective regulatory mechanisms can result in poor oxygen delivery even in the presence of adequate overall tissue perfusion. Restoration of endothelial function, and specifically conducted responses, should be considered when addressing tissue hypoxemia and organ failure in clinical settings.
Topics: Adaptation, Physiological; Hemodynamics; Humans; Hypoxia; Microcirculation; Oxygen; Oxygen Consumption
PubMed: 35581743
DOI: 10.14814/phy2.15303 -
Lakartidningen May 2016The inner side of the endothelium is covered by a thin layer of glycosylated proteins called the glycocalyx, which binds plasma to its surface up to a total thickness of... (Review)
Review
The inner side of the endothelium is covered by a thin layer of glycosylated proteins called the glycocalyx, which binds plasma to its surface up to a total thickness of 1-3 µm. The glycocalyx governs the endothelial permeability for macromolecules and has a key role in the regulation of microvascular perfusion. The glycocalyx also prevents adhesion of thrombocytes to the endothelial surface and counteracts microthrombosis by harbouring antithrombin III and thrombomodulin in its plasma layer. Knowledge about the ultrastructure of the glycocalyx has resulted in a revision of the Starling equation, which currently takes little notice of the oncotic pressure of the interstitial fluid space. The glycocalyx is involved in the initiation of the inflammatory response and is easily broken down (shedded) in response to sepsis, trauma, surgery, and cardiovascular disease. A shedded glycocalyx layer seems to impair the prognosis of heart failure and kidney disease. Its role as a mediator of cardiovascular complications to chronic disease is currently an important research topic.
Topics: Albuminuria; Capillary Permeability; Cardiovascular Diseases; Endothelial Cells; Endothelium, Vascular; Glycocalyx; Humans; Microcirculation
PubMed: 27187696
DOI: No ID Found -
Medicine Feb 2024Hemodynamic coherence plays a critical role in the outcomes of septic shock. Due to the potential negative consequences of microcirculatory disorders on organ failure... (Review)
Review
Hemodynamic coherence plays a critical role in the outcomes of septic shock. Due to the potential negative consequences of microcirculatory disorders on organ failure and clinical outcomes, the maintenance of a balance between the macrocirculation and microcirculation is a topic of significant research focus. Although physical methods and specialized imaging techniques are used in clinical practice to assess microcirculation, the use of monitoring devices is not widespread. The integration of microcirculation research tools into clinical practice poses a significant challenge for the future. Consequently, this review aims to evaluate the impact of septic shock on the microcirculation, the methods used to monitor the microcirculation and highlight the importance of microcirculation in the treatment of critically ill patients. In addition, it proposes an evaluation framework that integrates microcirculation monitoring with macrocirculatory parameters. The optimal approach should encompass dynamic, multiparametric, individualized, and continuous monitoring of both the macrocirculation and microcirculation, particularly in cases of hemodynamic separation.
Topics: Humans; Shock, Septic; Microcirculation; Hemodynamics; Critical Illness
PubMed: 38394485
DOI: 10.1097/MD.0000000000037273 -
Journal of the American Society of... Sep 2022The glomerular vascular pole is the gate for the afferent and efferent arterioles and mesangial cells and a frequent location of peripolar cells with an unclear...
The glomerular vascular pole is the gate for the afferent and efferent arterioles and mesangial cells and a frequent location of peripolar cells with an unclear function. It has been studied in definitive detail for >30 years, and functionally interrogated in the context of signal transduction from the macula densa to the mesangial cells and afferent arteriolar smooth muscle cells from 10 to 20 years ago. Two recent discoveries shed additional light on the vascular pole, with possibly far-reaching implications. One, which uses novel serial section electron microscopy, reveals a shorter capillary pathway between the basins of the afferent and efferent arterioles. Such a pathway, when patent, may short-circuit the multitude of capillaries in the glomerular tuft. Notably, this shorter capillary route is enclosed within the glomerular mesangium. The second study used anti-Thy1.1-induced mesangiolysis and intravital microscopy to unequivocally establish the long-suspected contractile function of mesangial cells, which have the ability to change the geometry and curvature of glomerular capillaries. These studies led me to hypothesize the existence of a glomerular perfusion rheostat, in which the shorter path periodically fluctuates between being more and less patent. This action reduces or increases blood flow through the entire glomerular capillary tuft. A corollary is that the GFR is a net product of balance between the states of capillary perfusion, and that deviations from the balanced state would increase or decrease GFR. Taken together, these studies may pave the way to a more profound understanding of glomerular microcirculation under basal conditions and in progression of glomerulopathies.
Topics: Microcirculation; Kidney Glomerulus; Glomerular Mesangium; Arterioles; Kidney Tubules
PubMed: 35853715
DOI: 10.1681/ASN.2022030354 -
Medical Sciences (Basel, Switzerland) Aug 2021A large number of models are now available for the investigation of skin wound healing. These can be used to study the processes that take place in a phase-specific... (Review)
Review
A large number of models are now available for the investigation of skin wound healing. These can be used to study the processes that take place in a phase-specific manner under both physiological and pathological conditions. Most models focus on wound closure, which is a crucial parameter for wound healing. However, vascular supply plays an equally important role and corresponding models for selective or parallel investigation of microcirculation regeneration and angiogenesis are also described. In this review article, we therefore focus on the different levels of investigation of skin wound healing (in vivo to in virtuo) and the investigation of angiogenesis and its parameters.
Topics: Microcirculation; Models, Theoretical; Skin; Wound Healing
PubMed: 34449673
DOI: 10.3390/medsci9030055 -
American Journal of Physiology. Heart... May 2022Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of... (Review)
Review
Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.
Topics: Coronary Circulation; Coronary Vessels; Endothelium, Vascular; Humans; Hypertension; Microcirculation; Microvessels
PubMed: 35333122
DOI: 10.1152/ajpheart.00603.2021